FR3039858A1 - CYLINDER HEAD FOR AN INTERNAL COMBUSTION ENGINE, ENGINE COMPRISING SAID CYLINDER HEAD AND METHOD OF MANUFACTURING SUCH CULASSE - Google Patents

Abstract

The present invention relates to a cylinder head (10) for an internal combustion engine (1), including a tablature (40) and valve seats (50) intended to be positioned facing a cylinder block (2); gas exchange conduits (60) extending from the valve seats (50) to intake and exhaust ports (64); and a water chamber (70) having a floor (72) and a ceiling (74). The cylinder head (10) is characterized in that the cylinder head (10) comprises a first module (20) including at least one pair (51, 52) of valve seats (50) and an inter-valve bridge (58); and a second module (30) including at least the ceiling (74) of the water chamber (70). The invention also relates to an engine (1) comprising such a cylinder head (10), as well as a method of manufacturing such a cylinder head (10).

Description

CYLINDER HEAD FOR AN INTERNAL COMBUSTION ENGINE, ENGINE COMPRISING SAID CYLINDER HEAD AND METHOD OF MANUFACTURING SUCH CULASSE

The present invention relates to a modular cylinder head for an internal combustion engine, in particular an internal combustion engine. The invention also relates to an engine comprising such a cylinder head, and a method of manufacturing such a cylinder head. The field of the invention is that of motor cylinder heads for motor vehicles, special machines, industrial or marine equipment.

Conventionally, the engine cylinder heads are cast in one piece, using a foundry process. This part comprises a lower part called "face fire" or "face combustion", seat of the explosion, arranged next to the pistons. Also, this part comprises an upper part integrating the water chamber (cylinder cooling system), the oil channels providing lubrication and the camshaft bearings.

Control of the cylinder head molding process is essential to ensure the efficient performance of each of the above functions. The main parameters to be taken into consideration are the heat of the cylinder head (depends in particular on the surface conditions, the cleanliness and the design of the water chamber), its resistance in thermal fatigue (depends in particular on the mechanical characteristics and the states surface of the water chamber, as well as areas of inter-valve bridges), and the efficiency of the air-fuel mixture in the combustion chamber (depends in particular on the aerodynamic characteristics of the intake and exhaust ducts) .

In a context of downsizing, the geometry of the cylinder heads becomes more complex and the thermomechanical characteristics imposed by the specifications reach important levels. In fact, engines of smaller displacement, and powers equal to or greater than the previous generation, are subject to very large thermomechanical stresses. This complexification generates new issues of cored, water chamber, oil circuits, intake or exhaust ducts. Consequently, compromises on the design of the cylinder head are often necessary (simplified geometry, overthicknesses and modified radii of curvature).

In practice, the tablature, the bridges and the water chamber, including its ceiling, are the areas of the cylinder head most stressed when the engine is in operation. Cooling systems and appropriately sized fabric thicknesses make it possible to meet the stresses exerted on the tablature and the bridges. On the other hand, it is much more complex to work on the water chamber, which therefore presents a risk of cracking. WO 2008 009 834 describes an example of a cylinder head, comprising a perforated element extending along the tablature and coated with the aluminum alloy forming the cylinder head. Thus, the tablature is reinforced with respect to the bending forces experienced during operation of the engine. EP 0 394 832 describes another example of a cylinder head consisting of two superimposed modules. The first module includes the tablature, the valve seats and the gas exchange channels, while the second module includes the valve control means. The tablature and the corresponding connecting part formed on the cylinder block are mirror-symmetrical with respect to a longitudinal axis of the engine, to create two possible connection positions between the first module and the cylinder block. Thus, the engine can be formed by assembling two cylinder head modules and a multi-purpose cylinder block, provided to adapt to the desired configuration of the engine. GB 1 031 571 describes another example of a cylinder head consisting of two superimposed modules. The first module includes tablature, valve seats, part of the gas intake channels and all gas exhaust channels. The second module includes the valve control means and the other portion of the gas intake channels. The first module is cooled by a water chamber, while the second module is cooled by air.

The object of the present invention is to provide an improved cylinder head, particularly in terms of resistance to thermomechanical stresses. For this purpose, the subject of the invention is a cylinder head for an internal combustion engine, including a tablature and valve seats intended to be positioned facing a cylinder block; gas exchange conduits extending from the valve seats to intake and exhaust ports; and a water chamber having a floor and a ceiling. The cylinder head is characterized in that it comprises a first module including at least one pair of valve seats and a jumper intersole; and a second module including at least the ceiling of the water chamber.

Thus, the invention optimizes the thermomechanical characteristics of the sensitive parts of the modular yoke, namely the tablature, the trigger guard and the water chamber. The manufacturing processes, and therefore the surface states of these parts, are better controlled. The risk of crack is reduced. Also, the web thicknesses and the number of machining operations can be reduced.

The cylinder head design offers greater flexibility. It is easier to modify the geometry of one of the modules, as well as to add or remove a function to the cylinder head. The modules are interchangeable depending on the type of engine, which gives great versatility to the cylinder head. It is possible to provide several designs of cylinder heads, with first interchangeable modules, and second interchangeable modules. The invention also relates to an internal combustion engine, characterized in that it comprises a cylinder head as mentioned above. The invention also relates to a method of manufacturing a cylinder head as mentioned above. The method is characterized in that it comprises the following steps: a) a separate manufacturing step of the first module and the second module, in particular by forging and / or casting; then b) a step of assembling the first module and the second module, for example by welding, gluing, bolt and joint clamping, or casting insertion.

According to other advantageous features of the invention, taken separately or in combination: the first module includes the tablature, the intake and exhaust ports, and the floor of the water chamber. - The first module includes the tablature, while the second module includes the intake and exhaust ports, and the floor of the water chamber. - The first module includes a first part of the tablature, while the second module includes a second part of the tablature, the intake and exhaust ports, and the floor of the water chamber. - The second module includes the tablature, the intake and exhaust ports, and the floor of the water chamber. - The cylinder head includes a plurality of first modules, each including at least one pair of valve seats and an inter-valve bridge. - The first module and the second module are made of two different materials. - The first module is made of a material more resistant to thermomechanical stresses than the second module. - The second module is made of secondary alloy. - The first module and the second module are each made by casting and forging. - When the cylinder head comprises several first modules, the first modules and the second module are assembled by insertion to the casting. - The floor and the ceiling of the water chamber have an arithmetic mean roughness Ra of between 19 and 24 pm and an average roughness without peaks and isolated cavities Rf between 38 and 50 pm. The invention will be better understood on reading the description which follows, given solely by way of nonlimiting example and with reference to the appended drawings in which: FIG. 1 is a partial perspective view of an explosion engine according to the invention, comprising a cylinder block and a cylinder head also according to the invention; Figure 2 is a side view of the cylinder head, according to the arrow II in Figure 1; Figure 3 is a section along the line III-III in Figure 2; Figure 4 is a section along the line IV-IV in Figure 2; Figure 5 is a view similar to Figure 1 showing a cylinder head according to a second embodiment of the invention; Figure 6 is a side view along the arrow II in Figure 1; Figure 7 is a section along the line VII-VII in Figure 6; Figure 8 is a section along the line VIII-VIII in Figure 6; Figure 9 is a view similar to Figure 1, showing a yoke according to a third embodiment of the invention; Figure 10 is a side view along the arrow X in Figure 9; Figure 11 is a section along line XI-XI in Figure 10; Figure 12 is an elevational view along the arrow XII in Figure 10; and Figures 13, 14 and 15 are perspective views similar to Figure 1 showing yokes respectively conforming to a fourth, a fifth and a sixth embodiment of the invention.

In Figures 1 to 4 is shown partially and schematically a combustion engine 1 according to the invention. The engine 1 comprises a cylinder block 2 and a cylinder head 10, also in accordance with the invention. The cylinder block 2 is represented by three dotted lines, only in Figure 1, for the sake of simplification.

The yoke 10 comprises a lower face 11 arranged facing the cylinder block 2, an upper face 12 disposed opposite the cylinder block 2, and four side faces 13, 14, 15 and 16.

In the context of the invention, the yoke 10 is constituted by a first module 20 and second module 30. In other words, the yoke 10 is modular, which optimizes the thermomechanical characteristics of its sensitive parts. The module 20 forms the lower part of the cylinder head 10, called "fire face" or "combustion face", while the module 30 forms the upper part of the cylinder head 10.

Modules 20 and 30 can be made of light alloys (aluminum, magnesium) or ferrous alloys (cast iron, steel). Advantageously, the modules 20 and 30 can be made of two different materials. For example, the modules 20 and 30 may be made of two different aluminum alloys, or the module 20 may be made of aluminum alloy while the module 30 is made of cast iron. According to a particular embodiment, the module 30 may be made of a secondary alloy, which makes it possible to reduce the manufacturing cost of the cylinder head 10.

The modules 20 and 30 may be manufactured separately, in particular by forging and / or casting. The modules 20 and 30 may be manufactured using the same manufacturing method, or two distinct processes. Preferably, each module 20 or 30 is fabricated by casting and forging, in accordance with the COBAPRESS (Trade Mark) method, of forging a foundry preform.

The modules 20 and 30 are assembled at a joint plane 18. The modules 20 and 30 can be secured by welding, gluing and / or tightening by bolts and seals. For example, the modules 20 and 30 are secured by gluing in the joint plane 18 and then by screwing, using long screws which pass through the cylinder head 10 and are fixed in the cylinder block 2.

The cylinder head 10 comprises a tablature 40, valve seats 50, an inter-valve bridge 58, gas exchange pipes 60, intake and exhaust ports 64, and a water chamber 70 having a floor 72 and a ceiling 74. These elements are distributed on the modules 20 and 30, as detailed below. Thanks to the modular construction of the cylinder head 10, the manufacture of each of these elements is better controlled, in comparison with a monobloc cylinder head. Thus, the thermomechanical characteristics of these elements, and in particular their surface states, are better controlled.

Furthermore, the cylinder head 10 may be provided with an intake manifold, an exhaust manifold, lubrication circuits and camshaft bearings, not shown for simplification purposes. The distributor and the collector are connected to the orifices 64. The lubrication circuits pass through the modules 20 and 30. The camshaft bearings are formed on the upper face 12 of the cylinder head 10, on the module 30.

The module 20 comprises the tablature 40, the valve seats 50, the intersoupape bridge 58, the gas exchange ducts 60, the intake and exhaust ports 64, and the floor 72 of the water chamber. 70.

The module 20 is positioned against the cylinder block 2, at the face 11. The module 20 directly cash the thermomechanical stresses generated by the explosion occurring in the cylinder block 2, when the engine 1 is in operation. In particular, these thermomechanical stresses are exerted on tablature 40, valve seats 50 and inter-valve bridge 58.

The module 30 comprises the ceiling 74 of the water chamber 70. Since the module 20 is interposed between the module 30 and the cylinder block 2, the module 30 is not directly stressed during the explosion in the block. cylinders 2. However, the water chamber 70 is subjected to significant constraints when the engine 1 is in operation. Thus, making the chamber 70 in two parts 72 and 74 distributed over the modules 20 and 30 makes it possible to optimize its characteristics, in particular its surface state. The risk of cracking is thus reduced.

In the example of Figures 1 to 4, the module 30 has grooves 32 extending between the faces 15 and 16 of the yoke 10. These grooves 32 can receive industrial glue to secure the modules 20 and 30. Alternatively, the grooves 32 may have other shapes and / or arrangements. Alternatively or in addition, the cylinder head 10 may be provided with other means facilitating assembly of the modules 20 and 30.

The tablature 40 is the wall interposed between, on the one hand, the combustion chamber located in the cylinder block 2 and, on the other hand, the ducts 60 and the water chamber 70 formed in the cylinder head 10. thickness of the tablature 40 is for example between 10 and 15 millimeters. In practice, this thickness depends on the dimensions of the engine 1.

The tablature 40 has a flat surface 48 located on the face 11. This surface 48 is disposed in contact with the cylinder head gasket, not shown, and the cylinder block 2. The valve seats 50 are set back in the module 20 by As a variant, the valve seats 50 can be flush with the surface 48.

In the example of FIGS. 1 to 4, the cylinder head 10 comprises a pair of valve seats 51 and 52, a pair of gas exchange ducts 61 and 62, and a pair of intake and exhaust ports. 65 and 66. A single bridge 58 is thus formed between the valve seats 51 and 52. Alternatively, depending on the type of engine 1, the cylinder head 10 may include more than two valve seats 50, a bridge 58, two pipes 60 and two orifices 64.

The gas exchange ducts 60 extend from the valve seats 50 to the intake and exhaust ports 64. More specifically, the duct 61 extends between the valve seat 51 and the air port. intake 65 open on the face 15, while the conduit 62 extends between the valve seat 51 and the exhaust port 66 open on the face 16. The orifice 65 is connected to the intake manifold, while that the orifice 66 is connected to the exhaust manifold.

The water chamber 70 forms the cooling system of the cylinder head 10. Preferably, the coolant circulating in the chamber 70 is brine. The chamber 70 extends through the yoke 10 in the vicinity of the ducts 60, between two orifices 75 and 76. For example, the orifice 76 may constitute the water inlet, while the orifice 75 constitutes the outlet of 'water.

In the example of Figures 1 to 4, the joint plane 18 is located in the middle of the chamber 70, so that the floor 72 belongs to the module 20, while the ceiling 74 belongs to the module 30. Manufacture the chamber 70 in two parts 72 and 74 distributed over the modules 20 and 30 makes it possible to improve its surface state, and therefore to reduce the risk of cracking. Also, this makes it possible to design complex chamber geometries 70 that are not feasible by conventional coring. In addition, this makes it possible to eliminate the risk of soiling caused by the presence of residual sand in the chamber 70. By way of example, the implementation of the invention makes it possible to obtain, for the floor 72 and the ceiling 74 of the chamber 70, an arithmetic average roughness Ra of between 19 and 24 pm and an average roughness without the isolated peaks and troughs Rf between 38 and 50 pm. These roughnesses are close to those obtained for the surface 48 of tablature 40. The roughness Rf is defined by the CNOMO standard (Committee for the Standardization of Production Mediums). Preferably, the roughness Ra is of the order of 22 μm, whereas the roughness Rf is of the order of 46 μm. Other embodiments of a cylinder head 10 according to the invention are shown in FIGS. 5 to 15. Certain constituent elements of the cylinder head 10 are comparable to those of the first embodiment described above and, for simplification purposes. , bear the same numerical references.

Figures 5 to 8 show a cylinder head 10 according to a second embodiment of the invention.

The module 20 comprises the tablature 40, the valve seats 50, the intersoupape bridge 58, and a part of the gas exchange conduits 60. The module 30 comprises the other part of the gas exchange conduits 60, the orifices intake and exhaust 64, as well as the floor 72 and the ceiling 74 of the water chamber 70.

The joint plane 18 is no longer located in the middle of the water chamber 70, however it is still possible to improve the manufacture of this chamber 70, in comparison with a monobloc cylinder head.

Figures 9 to 12 show a cylinder head 10 according to a third embodiment of the invention.

The module 20 comprises a first portion 42 of the tablature 40, the valve seats 50, the inter-valve bridge 58, and a portion of the gas exchange conduits 60. The module 30 comprises a second portion 44 of the tablature 40 , the other part of the gas exchange ducts 60, the intake and exhaust ports 64, as well as the floor 72 and the ceiling 74 of the water chamber 70.

The modules 20 and 30 are preferably secured by insertion to the casting. More specifically, the module 30 is cast around the module 20. The parts 42 and 44 of the tablature 40 are secured at a junction surface 19.

As a variant, the module 20 may have smaller dimensions, so that the module 30 comprises the entire tablature 40.

Figure 13 shows a yoke 10 according to a fourth embodiment of the invention.

This fourth mode is similar to the first mode, except that the cylinder head 10 is designed to equip a six-cylinder engine 1. The module 20 comprises the tablature 40, the six valve seats 50, the three inter-valve bridges 58, the six gas exchange ducts 60, the six intake and exhaust ports 64, as well as the floor 72 of the water chamber 70. The module 30 comprises the ceiling 74 of the water chamber 70.

Figure 14 shows a cylinder head 10 according to a fifth embodiment of the invention.

This fifth mode is similar to the second mode, except that the cylinder head 10 is designed to equip a six-cylinder engine 1. The module 20 comprises the tablature 40, six valve seats 50, three inter-valve bridges 58, and part of the six gas exchange ducts 60. The module 30 comprises the other part of the six gas exchange ducts. 60, the six intake and exhaust ports 64, as well as the floor 72 and the ceiling 74 of the water chamber 70.

Figure 15 shows a cylinder head 10 according to a sixth embodiment of the invention.

This sixth mode is similar to the third mode, except that the cylinder head 10 is designed to equip a six-cylinder engine 1, and comprises three modules 20 assembled with a single module 30. Each module 20 comprises a part of the tablature 40, two seats valve 50, an inter-valve bridge 58, and a portion of the six gas exchange conduits 60. The module 30 comprises the remainder of the tablature 40, the other portion of the conduits 60, the six inlet ports and exhaust 64, and the floor 72 and the ceiling 74 of the water chamber 70.

The modules 20 and 30 are preferably secured by insertion to the casting. More specifically, the module 30 is cast around the modules 20.

As a variant, the modules 20 may have smaller dimensions, so that the module 30 comprises the entire tablature 40.

Furthermore, the yoke 10 may be shaped differently from Figures 1 to 15 without departing from the scope of the invention.

Whatever the embodiment, the yoke 10 comprises at least a first module 20 which includes at least one pair of valve seats 51 and 52 and an intersoupape bridge 58; and a second module 30 which includes at least the ceiling 74 of the water chamber 70.

In addition, the technical characteristics of the various embodiments and variants mentioned above may be, in whole or in part, combined with one another. Thus, the cylinder head 10 can be adapted in terms of cost, modularity, functionality and performance.

Claims (10)

A cylinder head (10) for an internal combustion engine (1), including: a tablature (40) and valve seats (50) for positioning opposite a cylinder block (2); gas exchange conduits (60) extending from the valve seats (50) to intake and exhaust ports (64); and a water chamber (70) having a floor (72) and a ceiling (74); characterized in that the yoke (10) comprises: a first module (20) including at least one pair (51, 52) of valve seats (50) and an inter-valve bridge (58); and a second module (30) including at least the ceiling (74) of the water chamber (70). 2. Cylinder head (10) according to claim 1, characterized in that the first module (20) includes the tablature (40), the intake and exhaust ports (64), and the floor (72) of the chamber of water (70). Cylinder head (10) according to claim 1, characterized in that the first module (20) includes the tab (40), while the second module (30) includes the intake and exhaust ports (64), and the floor (72) of the water chamber (70). Cylinder head (10) according to claim 1, characterized in that the first module (20) includes a first portion (42) of the tablature (40), while the second module (30) includes a second portion (44) tablature (40), the intake and exhaust ports (64), and the floor (72) of the water chamber (70). Cylinder head (10) according to claim 1, characterized in that the second module (30) includes the tablature (40), the intake and exhaust ports (64), and the floor (72) of the chamber of water (70). 6. Cylinder head (10) according to one of claims 4 or 5, characterized in that it comprises a plurality of first modules (20), each including at least one pair (51, 52) of valve seats (50) and a inter-valve bridge (58). 7. Cylinder head (10) according to one of the preceding claims, characterized in that the first module (20) and the second module (30) are made of two different materials. 8. Cylinder head (10) according to one of the preceding claims, characterized in that the floor (72) and the ceiling (74) of the water chamber (70) have an arithmetic average roughness Ra between 19 and 24 pm and an average roughness with no isolated peaks and troughs Rf between 38 and 50 μm. 9. Internal combustion engine (1), characterized in that it comprises a yoke (10) according to one of claims 1 to 8. 10. A method of manufacturing a yoke (10) according to one of claims 1 to 8, characterized in that it comprises the following steps: a) a separate manufacturing step of the first module (20) and the second module (30), especially by forging and / or casting; then b) a step of assembling the first module (20) and the second module (30), for example by welding, bonding, bolt and joint clamping, or casting insertion.